Metal extracting agent, metal ion separation and recovery method using same, and compound

Abstract

A compound and a metal extractant for extracting metal ions present in an aqueous phase into an oil phase, the compound and metal extractant having a structure represented by formula (I) and not having a nitrogen atom, and a method for separating and recovering metal ions using the metal extractant. In formula (I), R1 represents a hydrogen atom, a metal atom, or a monovalent substituent, X represents a monovalent substituent including at least one of an oxygen atom, a sulfur atom, and a phosphorus atom, and the benzene ring in the formula may form a fused ring. Formula (I)

Description

Technical Field

[0001] This invention relates to a metal extractant for extracting metal ions present in an aqueous phase into an oil phase, a method for separating and recovering metal ions using the metal extractant, and a compound. Background Technology

[0002] Valuable metals such as precious metals and rare earth metals are essential elements for precision equipment, making their stable and high-purity supply a major challenge. These valuable metals are typically mined as mixtures with other metals, necessitating the separation and purification (high-purity) of the target valuable metal from these mixtures. Furthermore, the amount of valuable metals that can be mined is limited, thus technologies for recovering valuable metals from industrial waste without relying on mining are gaining importance. In particular, with the increasing prevalence of electric vehicles, the amount of waste from lithium-ion batteries (LiB) is increasing annually. LiB uses positive electrode active materials containing metals such as cobalt and nickel, and the demand for cobalt and nickel is expected to increase significantly. To address the increasing demand for valuable metals accompanying this trend, it is desirable not only to increase mining volume but also to establish technologies for recovering metals from waste LiB.

[0003] Wet extraction (solvent extraction) is used as a method for separating and purifying target valuable metals from mining mixtures and for recovering metals from waste. In wet extraction, an organic phase containing a metal extractant is contacted with an aqueous solution (aqueous phase) containing metal ions (referred to as metal ions) and mixed. The mixture is then allowed to stand, causing the two phases to separate. This allows the metal ions coordinated with the metal extractant to move (extract) into the organic phase. The organic phase is then removed, and the metal ions are back-extracted. Purification is then performed as needed, thereby enabling the separation and purification of the target metal and the recovery of (high-purity) metals.

[0004] As metal extractants used in this wet extraction method, for example, Patent Document 1 describes an extractant containing a mixture of quaternary ammonium compounds such as methyltri-n-octylammonium chloride and phenol compounds such as nonylphenol. Furthermore, Patent Document 2 describes a second mixed extractant containing a phosphate ester extractant such as di-2-ethylhexylphosphate and an oxime extractant such as 5-nonylsalicylaldehyde oxime.

[0005] Previous technical documents

[0006] Patent documents

[0007] Patent Document 1: Japanese Patent Application Publication No. 2013-133537

[0008] Patent Document 2: Japanese Patent Application Publication No. 2016-194105 Summary of the Invention

[0009] The technical problem to be solved by the invention

[0010] Patent documents 1 and 2 describe the following: The metal extractants described in patent documents 1 and 2, by combining two specific extractants and using a wet extraction method, can extract specific metal ions present in the aqueous phase into the oil phase and recover them. However, when using two specific extractants separately in a wet extraction method, the selectivity (separation ability) of the extracted metal ions is insufficient. Therefore, it is desirable to have a metal extractant with high initial selectivity for selectively separating and extracting specific metal ions from the aqueous phase in a wet extraction method.

[0011] Regarding extraction conditions such as temperature and pressure (contact conditions between the aqueous and oil phases), wet extraction is typically carried out under relatively mild conditions. Therefore, from the viewpoint of reducing recovery costs, metal extractants are often repeatedly used. However, in wet extraction, when the aqueous and oil phases are brought into contact, or during back-extraction and separation of metal ions extracted into the oil phase, the mixture of the aqueous and oil phases is set to a predetermined pH, making it relatively strongly acidic or alkaline (for example, see Patent Documents 1 and 2). If wet extraction is repeatedly performed under these pH conditions, even with metal extractants exhibiting high selectivity for metal ions, the amount of metal ions extracted from the aqueous phase to the oil phase will gradually decrease. Therefore, it is desirable to use metal extractants with high durability in maintaining the recovery rate (extraction rate) of metal ions even with repeated wet extraction.

[0012] However, neither Patent Documents 1 nor 2 conducted any research on further improving the selectivity of metal ions, nor did they conduct any research on suppressing the decrease in the recovery rate of metal ions during repeated use.

[0013] The objective of this invention is to provide a metal extractant capable of highly selectively extracting specific metal ions present in an aqueous phase into an oil phase and exhibiting high durability, as well as a method for separating and recovering metal ions using the metal extractant. Furthermore, the objective of this invention is to provide a compound capable of becoming a metal extractant exhibiting the aforementioned superior properties.

[0014] means for solving technical problems

[0015] The inventors conducted in-depth research on metal extractants used in wet extraction methods and discovered the following: In the case of a phenolic structure (formula (I) described below), the "benzene ring-OR" structure... 1 Based on the structure indicated by "", a monovalent substituent containing at least one of oxygen, sulfur and phosphorus atoms is introduced into its benzene ring to prepare a compound that does not contain nitrogen atoms. Thus, when this compound is used as a metal extractant in wet extraction, it can maintain high selectivity (separation ability) of metal ions while suppressing the reduction of metal ion extraction amount for a long time.

[0016] Based on these insights, the present invention underwent further and repeated research to complete the present invention.

[0017] That is, the above problems can be solved by the following solution.

[0018] <1> A metal extractant, which is a metal extractant for extracting metal ions present in the aqueous phase into the oil phase, wherein,

[0019] The metal extractant has a structure represented by the following formula (I) and does not have nitrogen atoms.

[0020] [Chemical Formula 1]

[0021]

[0022] In equation (I), R 1 It represents a hydrogen atom, a metal atom, or a monovalent substituent.

[0023] X represents a monovalent substituent containing at least one of the following: oxygen, sulfur, and phosphorus atoms.

[0024] The benzene ring in formula (I) can form a fused ring.

[0025] <2> The metal extractant according to <1>, wherein the metal extractant has a functional group selected from the functional group G below.

[0026] <Functional Group G>

[0027] Carboxyl group, phosphate group, phosphonic acid group, hypophosphonic acid group, sulfonic acid group, sulfinic acid group.

[0028] <3> The metal extractant according to <2>, wherein the functional group selected from functional group G is a phosphate group or a phosphonic acid group.

[0029] <4> The metal extractant according to any one of <1> to <3>, wherein the metal extractant has a hydrocarbon group having 9 or more carbon atoms.

[0030] <5> The metal extractant according to any one of <1> to <4>, wherein the metal extractant is represented by the following formula (II).

[0031] [Chemical Formula 2]

[0032]

[0033] In equation (II), R 1 It represents a hydrogen atom, a metal atom, or a monovalent substituent.

[0034] L represents a divalent linker containing at least one of the following: oxygen, sulfur, and phosphorus atoms, but not a nitrogen atom.

[0035] R 2 It represents a hydrocarbon group with 8 or more carbon atoms. However, when L is a carbonyl group, it represents a hydrocarbon group with 8 or more hydrogen atoms.

[0036] The benzene ring in formula (II) can form a fused ring.

[0037] <6> The metal extractant according to any one of <1> to <5>, wherein the metal ion is an ion of a metal element belonging to Group 1 to Group 14 of the periodic table.

[0038] <7> The metal extractant according to any one of <1> to <6> is used to extract and separate two or more metal ions belonging to different groups in the periodic table from the metal ions.

[0039] <8> A method for separating and recovering metal ions, wherein an aqueous phase containing multiple metal ions and an oil phase containing any one of the metal extractants described in <1> to <7> are mixed.

[0040] <9> A compound represented by the following formula (II).

[0041] [Chemical Formula 3]

[0042]

[0043] In equation (II), R 1 This indicates a hydrogen atom, a metal atom, or a monovalent substituent.

[0044] L represents a divalent linker containing at least one of the following: oxygen, sulfur, and phosphorus atoms, but not a nitrogen atom.

[0045] R 2 It represents a hydrocarbon group with 8 or more carbon atoms. However, when L is a carbonyl group, it represents a hydrocarbon group with 8 or more hydrogen atoms or carbon atoms.

[0046] The benzene ring in formula (II) can form a fused ring.

[0047] Invention Effects

[0048] The objective of this invention is to provide a metal extractant capable of highly selectively extracting specific metal ions present in an aqueous phase into an oil phase and exhibiting high durability, as well as a method for separating and recovering metal ions using the metal extractant. Furthermore, the objective of this invention is to provide a compound capable of becoming a metal extractant exhibiting the aforementioned superior properties.

[0049] The above-described features and other features and advantages of the present invention will become more apparent from the accompanying drawings and from the following description. Attached Figure Description

[0050] Figure 1 It is the compound E-1 synthesized in the examples. 1 H-NMR spectrum. Detailed Implementation

[0051] In this invention, when numerical ranges are shown to describe the content, physical properties, etc. of a component, and the upper and lower limits of the numerical range are described separately, any appropriate combination of the upper and lower limits can be used to define a specific numerical range. On the other hand, when multiple numerical ranges represented by "~" are defined and described, the upper and lower limits forming the numerical range are not limited to a specific combination before and after "~" as a specific numerical range; a numerical range can be defined as an appropriate combination of the upper and lower limits of each numerical range. Furthermore, in this invention, the numerical range represented by "~" refers to a range that includes the values ​​before and after "~" as both the lower and upper limits.

[0052] In this invention, the designation of a compound (e.g., when referred to as a compound by appending a compound at the end) means that in addition to the compound itself, it also includes its salt and its ions. Furthermore, it means that, to a extent that it does not impair the effects of this invention, it includes derivatives that modify a portion by introducing substituents or the like.

[0053] In this invention, the term "substituent, linking group, etc." (hereinafter referred to as "substituent, etc.") that is not explicitly stated as substituted or unsubstituted refers to the possibility of having suitable substituents in the group. Therefore, in this invention, even when simply stated as a YYY group, the YYY group includes both the form without substituents and the form with substituents. This also applies to compounds that are not explicitly stated as substituted or unsubstituted. Preferred substituents include, for example, groups selected from the substituents GZ described later.

[0054] In this invention, when multiple substituents, etc., are represented by specific symbols, or when multiple substituents, etc., are defined simultaneously or selectively, it means that each substituent, etc., can be the same as or different from each other. Furthermore, even without specific explanation, when multiple substituents, etc., are adjacent, it means that they can connect or fused together to form a ring.

[0055] In addition, in this specification, "metallic elements belonging to different groups in the periodic table" are sometimes referred to as "different group metal elements", and in particular, "different group metal elements in the same period of the periodic table" are referred to as "different group metal elements in the same period". Furthermore, "ions of different group metal elements" and "ions of different group metal elements in the same period" are sometimes referred to as "different group metal ions" and "different group metal ions in the same period", respectively.

[0056] In this invention, unless otherwise specified, "ppm" indicating content, etc., is a quality standard and means "mass ppm".

[0057] [Metal Extractant]

[0058] The metal extractant of the present invention comprises a compound represented by formula (I) as described later, and may appropriately contain other components without impairing the effectiveness of the present invention. Furthermore, in addition to the compound represented by formula (I), the metal extractant of the present invention may also contain other compounds that function as metal ion extractants (other metal extractants). However, as described later, the compound represented by formula (I) exhibits the aforementioned superior properties as a metal extractant, and therefore it is preferable to contain only the compound represented by formula (I). In the present invention, the metal extractant of the present invention containing only the compound represented by formula (I) means containing only the compound represented by formula (I) and containing other metal extractants in an amount of 10% by mass or less relative to the total amount of the compound represented by formula (I).

[0059] Furthermore, the form of the metal extractant and the compound represented by formula (I) of the present invention is not particularly limited, and can be in the form of solid such as powder or granules, or in the form of liquid (solution) dissolved in the organic solvent described later.

[0060] The metal extractant of the present invention exhibits the function of extracting metal ions present in the aqueous phase into the oil phase, and is particularly preferred for use in wet extraction methods. When the metal extractant of the present invention is used in a wet extraction method, even when comprising only a compound represented by formula (I), and even with prolonged use, specific metal ions present in the aqueous phase can be extracted into the oil phase with high selectivity and high recovery. In particular, this metal extractant can extract specific metal ions from a variety of metal ions present in the aqueous phase into the oil phase with high selectivity and high recovery.

[0061] In this invention, the metal ion that can be extracted from the oil phase among multiple metal ions present in the aqueous phase is ideally a single specific metal ion, but sometimes it is two or more metal ions. Even in the case of two or more metal ions, one of the metal ions can be extracted (separated and recovered) into the oil phase with high selectivity and high recovery rate relative to the other metal ions (including the metal ions extracted into the oil phase). For example, as ions of valuable metal elements, two or more heterogeneous metal ions, such as two or more metal ions belonging to Groups 1 to 14 of the periodic table (preferably two or more heterogeneous metal ions, especially heterogeneous metal ions of the same period, i.e., cobalt ions and nickel ions), can be extracted into the oil phase with high selectivity and high recovery rate.

[0062] Because dissimilar metal ions within the same period exhibit similar physical and chemical behaviors, it is not easy to selectively separate and recover any one of them. However, in this invention, which uses a compound represented by formula (I) as a metal extractant, it is possible to extract both dissimilar metal ions within the same period with similar physical and chemical behaviors, particularly Group 9 metal ions (especially cobalt ions) and Group 10 metal ions (especially nickel ions), which have become increasingly important due to the rapid proliferation of lithium-ion batteries in recent years. This allows for the selective and high-recovery recovery of one of the metal ions simultaneously. Therefore, this invention can greatly contribute to the further popularization of electric vehicles and, consequently, the construction of a sustainable society.

[0063] In this invention, the ability to selectively extract metal ions means being able to extract only one specific metal ion from a plurality of metal ions present in the aqueous phase. Furthermore, when extracting two or more metal ions in the oil phase, the ability to selectively extract metal ions means that, among the two or more metal ions extracted, the ratio of the extraction amount of the specific metal ion (usually one) as the extraction target to the total extraction amount of the other metal ions [(extraction amount of the specific metal ion) / (total extraction amount of the other metal ions)] can be extracted and separated from the other metal ions at a ratio (separation ability, selectivity) of 1.5 or higher. The aforementioned ratio (selectivity) is preferably 3.0 or higher, more preferably 4.5 or higher, and even more preferably 8.0 or higher. As an upper limit, there is no particular limitation; for example, it can be set to 30.

[0064] In this invention, the aforementioned ratio (selectivity ratio) refers to the ratio achieved when the metal extractant of this invention is first used in a wet extraction process. Furthermore, the metal extractant of this invention maintains high selectivity even when repeatedly used in a wet extraction process and when used continuously for extended periods. For example, a selectivity ratio of 1.5 or higher, more preferably 4.5 or higher, is preferred when used 10 times in the wet extraction process (separation extraction operation) described later in the embodiments.

[0065] Furthermore, in this invention, high recovery rate of metal ions means that, regarding the metal ions extracted at the maximum extraction rate (the specific metal ion targeted for extraction), the ratio of the amount of that metal ion extracted in the oil phase to its content in the aqueous phase (before extraction) [(amount of metal ions extracted in the oil phase) / (content of that metal ion in the aqueous phase)] can be extracted at a rate of 60% or more. This ratio (recovery rate) is preferably 80% or more, more preferably 90% or more, and even more preferably 95% or more. As an upper limit, there is no particular limitation; ideally, the total amount of that metal ion present in the aqueous phase (100%) is preferably 99% or less, for example.

[0066] In this invention, the aforementioned ratio (recovery rate) refers to the ratio achieved when the metal extractant of this invention is first used in a wet extraction process. Furthermore, the metal extractant of this invention exhibits excellent durability, thus maintaining a high recovery rate even when repeatedly used in a wet extraction process or used continuously for extended periods. For example, the recovery rate when used 10 times in the wet extraction process (separation extraction operation) described later is preferably 70% or more, more preferably 85% or more.

[0067] (Compounds represented by formula (I))

[0068] The metal extractant of the present invention is a compound having a (chemical) structure represented by the following formula (I), and is composed of a compound (sometimes referred to as the compound of the present invention) that does not have a nitrogen atom within its structure (molecule). As described above, this compound exhibits excellent properties as a metal extractant.

[0069] The compounds of this invention do not contain nitrogen atoms. In this invention, "compounds not containing nitrogen atoms" means that the atomic groups constituting the compound do not contain nitrogen atoms; for example, it means that neither the phenolic structure nor any of the substituents contains nitrogen atoms. Examples of substituents containing nitrogen atoms include amino groups and imino groups (-NR). N1 -、-C=NR N1 ), groups composed of nitrogen-containing aromatic rings or nitrogen-containing aliphatic rings, etc. The R in imino groups... N1 It represents a hydrogen atom or a substituent. As a substituent, groups selected from the substituents GZ described below can be cited. They usually represent alkyl groups with 1 to 6 carbon atoms, aryl groups with 6 to 10 carbon atoms, and hydroxyl groups.

[0070] The compounds of the present invention, possessing both high selectivity and high durability, can be used as metal extractants in wet extraction processes for extended periods, for example, repeatedly and continuously. The number of times the compounds of the present invention can be repeatedly used in wet extraction (number of uses) or the duration of continuous use cannot be uniquely determined by various conditions in the wet extraction process, the reverse extraction conditions of the metal ions, or appropriate purification conditions during reuse. For example, the number of uses in intermittent or other wet extraction processes can be set to 5 times or more, preferably 10 times or more, and the continuous use time in continuous or other wet extraction processes can be set to 12 hours or more, preferably 24 hours or more. Furthermore, the upper limits for the number of uses and the continuous use time can be appropriately determined by considering, in addition to the conditions mentioned above, the selectivity and recovery rate. For example, the number of uses can be set to 100 times or less, and from the viewpoint of achieving a high selectivity and high recovery rate within the aforementioned range, 50 times or less is preferred, and 30 times or less is more preferable. Furthermore, the continuous usage time can be set to 168 hours or less. From the viewpoint of achieving a high selectivity and high recovery rate within the aforementioned range, 48 hours or less is preferred, and 36 hours or less is even more preferred.

[0071] [Chemical Formula 4]

[0072]

[0073] In compounds represented by formula (I), the benzene ring in formula (I) can form a fused ring. For example, compounds represented by the above formula (IC) can be cited as examples of compounds forming a fused ring. In formula (IC), α represents the atomic group that forms a fused ring with the benzene ring in formula (IC) (however, it does not include a nitrogen atom.)

[0074] As the atomic group that can be used as α, any atomic group capable of forming a fused ring with the benzene ring in formula (IC) is acceptable. For example, atomic groups capable of forming fused rings without nitrogen atoms can be cited. The ring formed by α together with the benzene ring (2 carbon atoms) in formula (IC) is not particularly limited; it can be an aliphatic ring, an aromatic ring, a hydrocarbon ring, or a heterocyclic ring (except for those containing nitrogen atoms). Furthermore, the formed ring itself can be monocyclic or polycyclic. Specifically, examples of the ring formed by α include cycloalkyl, aryl, and heterocyclic groups in the substituent GZ described later.

[0075] In this invention, compounds that do not have α are preferred, i.e., compounds represented by formula (I).

[0076] In equations (I) and (IC), R 1 It represents a hydrogen atom, a metal atom, or a monovalent substituent.

[0077] In this invention, as a form that can be used as R1 The preferred first option is the use of atoms such as hydrogen atoms or metal atoms, more preferably hydrogen atoms. On the other hand, as a suitable candidate for R... 1 The second preferred embodiment is a substituent with a valent 1.

[0078] As can be used as R 1 The metal atom can be any atom capable of forming a salt of phenolic hydroxyl groups, preferably a monovalent metal atom. It can be used as R. 1 Metal atoms typically exist in the form of metal ions. Examples of such metal atoms include those belonging to Group 1 or Group 2 of the periodic table, with those belonging to Group 1 being preferred, and lithium, sodium, and potassium being more preferred.

[0079] As can be used as R 1 The monovalent substituent is not particularly limited and may be any substituent that does not contain a nitrogen atom. For example, groups selected from the substituents GZ described below (however, substituents that do not contain a nitrogen atom) are examples. As a monovalent substituent, alkyl, alkenyl, alkynyl, aryl, aralkyl, and other hydrocarbon groups, heterocyclic groups are preferred, alkyl or aryl groups are more preferred, and alkyl groups are even more preferred.

[0080] As can be used as R 1 The alkyl group in the alkyl, alkenyl, alkynyl and aralkyl groups is not particularly limited and can be any of the straight chain, branched chain and cyclic chain, but is preferably straight chain.

[0081] Regarding what can be used as R 1 The total number of carbon atoms constituting a monovalent substituent, especially a hydrocarbon group (hereinafter simply referred to as the number of carbon atoms), is independent of the description of the substituent GZ described later and is not particularly limited. The number of carbon atoms of each group is suitably determined, for example, in the range of 1 to 30. As a group that can be used as R... 1 The preferred first aspect of the number of carbon atoms of the monovalent substituent is 1 to 12 (corresponding to short-chain alkyl and medium-chain alkyl), more preferably 1 to 6 (corresponding to short-chain alkyl), and even more preferably 1 to 4 (corresponding to short-chain alkyl). As a possible R... 1 The preferred second option is that the number of carbon atoms of the monovalent substituent is 9 to 20 (corresponding to medium-chain alkyl and long-chain alkyl), more preferably 10 to 18, and even more preferably 12 to 16.

[0082] In formulas (I) and (IC), X represents a monovalent substituent containing at least one of an oxygen atom, a sulfur atom, and a phosphorus atom. This substituent typically does not contain a nitrogen atom.

[0083] A preferred first type of substituent for X is one in which the heteroatom is directly bonded to the benzene ring in formula (I) or formula (IC). In this type, the heteroatom included in the monovalent substituent is preferably a sulfur atom or a phosphorus atom, and may further include an oxygen atom. On the other hand, a preferred second type of substituent for X is one in which the heteroatom is not directly bonded to the benzene ring in formula (I) or formula (IC). In this type, the heteroatom included in the monovalent substituent is preferably an oxygen atom. In the second type of substituent, there are no particular limitations on the atoms directly bonded to the benzene ring in formula (I) or formula (IC), or on the linking group, etc. For example, atoms that are not equivalent to either the heteroatom or the nitrogen atom can be used; on the other hand, a linking group that uses atoms other than the heteroatom as the linking group (however, it does not include a nitrogen atom); or a group obtained by removing a hydrogen atom from a group selected from the substituents GZ described later; preferably, a carbon atom.

[0084] There is no particular limitation on the number of heteroatoms that can be included in the monovalent substituent of X. For example, it can be one or more, preferably two or three, and more preferably two. As a combination of two or more heteroatoms, a combination of phosphorus atom with oxygen atom and / or sulfur atom can be cited as an example.

[0085] The number of heteroatoms contained in the monovalent substituents that can be used as X is not particularly limited and can be appropriately determined according to the chemical structure of X. For example, the number of heteroatoms can be set to 1 to 12, preferably 2 to 8, and more preferably 2 to 5.

[0086] In the monovalent substituents that can be used as X, the heteroatom can be present in any of the monovalent substituents, for example, it can be present inside or at the end of the atomic chain constituting the monovalent substituent. In this invention, it is preferred that one heteroatom is present at the end of the atomic chain constituting the substituent and bonded to the benzene ring in formula (I) or formula (IC) above, and that one heteroatom forms a carbonyl group and is bonded to the benzene ring in formula (I) or formula (IC) above.

[0087] As a monovalent substituent that can be used as X, there are no particular limitations as long as it contains the aforementioned heteroatom. Examples of substituents included in substituent GZ described later include substituents that contain the aforementioned heteroatom but do not contain a nitrogen atom. From the viewpoint of being able to balance the selectivity and durability of the metal extractant at a higher level, the functional groups included in functional group G described later are preferred. Among the functional groups included in functional group G, examples of preferred monovalent substituents that can be used as the first embodiment include phosphate group, phosphonic acid group, hypophosphonic acid group, sulfonic acid group, and sulfinic acid group. Examples of preferred monovalent substituents that can be used as the second embodiment include carboxyl group.

[0088] As described above, the compound represented by formula (I) or formula (IC) employs a monovalent substituent as X. Therefore, this compound is a non-polymeric compound having a single structure represented by formula (I) or formula (IC) without using that structure as a repeating unit. Thus, the compound represented by formula (I) or formula (IC) does not employ a structure consisting of multiple structures represented by formula (I) or formula (IC) linked via X, such as linear structures and cyclic or tubular structures.

[0089] Compounds represented by formula (I) or formula (IC) can convert R in the formula 1 The symbols are formed by appropriately combining X and α, preferably by combining preferred symbols of each symbol with each other.

[0090] However, while compounds represented by formula (I) or formula (IC) can be basic compounds, from the viewpoint of exhibiting excellent selectivity and high durability as metal extractants, acidic compounds having at least one active hydrogen atom are preferred; that is, compounds represented by formula (I) or formula (IC) are equivalent to acidic metal extractants. Examples of active hydrogen atoms in the compound include hydroxyl groups (including phenolic hydroxyl groups and hydroxyl groups bonded to phosphorus or sulfur atoms), carboxyl groups, and thioalkyl groups. Active hydrogen atoms can be present in compounds represented by R... 1 It exists in any of the rings formed by X and α, but preferably in R. 1 Or in X. The number of hydroxyl groups present in the compound only needs to be one or more, and can be set to 1 to 4, preferably one or two.

[0091] In compounds represented by formula (I) or formula (IC), -OR 1 The bonding position of X with the benzene ring is not particularly restricted. For example, X relative to -OR 1 The group can be any of the 2-position (ortho), 3-position (meta), or 4-position (para), but from the viewpoint of being able to stably coordinate with metal ions to improve the selectivity and durability of the metal extractant, the 2-position is preferred.

[0092] Furthermore, in compounds represented by formula (IC), the position of the α-ring bonded to the benzene ring is determined as long as it does not impede the -OR bond. 1 The bonding of the radical to X on the benzene ring is not particularly limited. For example, relative to -OR 1 The base can be any one of 2 bits and 3 bits, 3 bits and 4 bits, 4 bits and 5 bits, or 5 bits and 6 bits, preferably OR. 1 The base and X are bonded separately. When X is bonded at position 2, it is more preferable to bond it at positions 4 and 5.

[0093] In this invention, from the viewpoint of the selectivity and durability of the metal extractant, the compound represented by formula (I) above is preferably the compound represented by formula (II) below. The case where neither the compound represented by formula (II) below nor the compound represented by formula (IIC) below has a nitrogen atom is the same as the case where the compound represented by formula (I) or formula (IC) above does not have a nitrogen atom.

[0094] [Chemical Formula 5]

[0095]

[0096] In equation (II), R 1 R in equation (I) above 1 same.

[0097] Furthermore, in the compounds represented by formula (II), the benzene ring in formula (II) can form a fused ring, just as in the compounds represented by (I) above. That is, compounds in which the benzene ring in formula (I) forms a fused ring are, for example, represented by the above formula (IIC). In formula (II), α represents an atomic group that forms a fused ring with the benzene ring in formula (IIC) (however, it does not contain a nitrogen atom), specifically, it is the same as α in formula (IC) above.

[0098] In this invention, compounds that do not have α are preferred, i.e., compounds represented by formula (II).

[0099] In equations (II) and (IIC), -LR 2 The preferred form of the base, which is a monovalent substituent of X in the above formulas (I) and (IC), is composed of the following L and the following R. 2 form.

[0100] Here, L represents a divalent linker containing at least one of oxygen, sulfur, and phosphorus atoms, but not a nitrogen atom. R 2 It represents a hydrocarbon group with 8 or more carbon atoms. However, when L is a carbonyl group, it represents a hydrocarbon group with 8 or more hydrogen atoms.

[0101] As a divalent linker for L, any linker can be a heteroatom containing at least one of oxygen, sulfur, or phosphorus atoms and not containing a nitrogen atom. There are no particular limitations on such a linker; examples include oxygen, sulfur, carbonyl, and phosphate linkers (-OP(=O)(OR). C )-O- group), phosphonic acid linker (-P(=O)(OR) C )-O- group), phosphonic acid linker (-P(=O)R C-O- group (However, phosphate linkers, phosphonic acid linkers, and hypophosphonic acid linkers include linkers that replace at least one oxygen atom in each group with a sulfur atom.) or groups related to combinations thereof. Here, R C Represents a hydrogen atom or substituent, and R in the functional group G described later. C same.

[0102] The number of groups, linkers, or atoms combined in the group related to the combination is not particularly limited; for example, it can be 2 to 15, preferably 2 to 10, and more preferably 2 to 5. Furthermore, the number of types of groups, linkers, or atoms combined is not particularly limited; for example, it can be 2 or more, preferably 2 or 3. Examples of groups related to the combination include carbonyl groups, sulfonic acid linkers (-S(=O)2-O-), and sulfinic acid linkers (-S(=O)-O-) (however, sulfonic acid linkers and sulfinic acid linkers include linkers in which at least one oxygen atom in each group is replaced by a sulfur atom.)

[0103] The number of connecting atoms in the aforementioned linking group is not particularly limited, but is preferably 15 or less, more preferably 10 or less, even more preferably 6 or less, and particularly preferably 4 or less. The lower limit is 1 or more. The aforementioned number of connecting atoms refers to the number of atoms connecting the benzene ring and R in formula (II) or formula (IIC). 2 The minimum number of atoms. The number of atoms constituting the above linker (the number of constituent atoms) cannot be determined by phosphate linkers, etc. C The value can be uniquely determined, for example, by setting it to 1 to 100, preferably 1 to 40, and more preferably 1 to 24.

[0104] A preferred first embodiment of the divalent linker for L is one in which the heteroatom is directly bonded to the benzene ring in formula (II) or (IIC). In this embodiment, the heteroatom contained in the divalent linker is preferably a sulfur atom or a phosphorus atom, and may further contain an oxygen atom. Conversely, a preferred second embodiment of the divalent linker for L is one in which the heteroatom is not directly bonded to the benzene ring in formula (II). In this embodiment, the heteroatom contained in the divalent linker is preferably an oxygen atom. In the second embodiment of the linker, the atom directly bonded to the benzene ring in formula (II) or (IIC), the linker, and other connecting portions are the same as the connecting portions in the preferred second embodiment of formulas (I) and (IC) for the monovalent substituents of X, and are preferably carbon atoms.

[0105] There are no particular restrictions on the number of heteroatoms and atoms contained in the divalent linking group that can be used as L, but it is preferred that the number of heteroatoms and atoms contained in the divalent substituent that can be used as X is the same.

[0106] In the linker that can be used as L, the heteroatom can be present in any of the divalent linkers, for example, it can be present inside or at the end of the atomic chain constituting the divalent linker. In this invention, it is preferred that one heteroatom is present at the end of the atomic chain constituting the linker and bonded to the benzene ring in formula (II) or (IIC) above, and that one heteroatom forms a carbonyl group and is bonded to the benzene ring in formula (II) or (IIC) above.

[0107] As a divalent linker that can be used as L, there are no particular limitations as long as it contains the aforementioned heteroatom and does not contain a nitrogen atom. Examples of substituents included in the substituent GZ described later include substituents containing the aforementioned heteroatom and not containing a nitrogen atom. From the viewpoint of achieving a higher level of balance between the selectivity and durability of the metal extractant, structures comprising the functional groups included in the functional group group G described later are preferred. Among the functional groups included in the functional group group G, preferred divalent linkers that can be used as the first embodiment include structures comprising phosphate, phosphonic acid, hypophosphonic acid, sulfonic acid, and sulfinic acid groups; specifically, structures in which R is removed from each group. C or R D The resulting structure, as a preferred divalent linker that can be used as the second approach, can be exemplified by structures constituting a carboxyl group, specifically a carbonyl group.

[0108] As can be used as R 2 The hydrocarbon group is not particularly limited; for example, alkyl, alkenyl, alkynyl, aryl, and aralkyl groups can be mentioned. From the viewpoint of being able to balance the selectivity and durability of metal extractants at a higher level, alkyl groups are preferred.

[0109] As can be used as R 2 The alkyl group in the alkyl, alkenyl, alkynyl, and aralkyl groups is not particularly limited and can be any of straight-chain, branched, or cyclic chains. However, from the viewpoint of achieving a higher level of selectivity and durability of the metal extractant, a branched chain is preferred. In applications where it can be used as R... 2 When the aforementioned alkyl group or the like is branched, there is no particular limitation as long as the number of branched carbon atoms in the group is one or more. A preferred first option for the number of branched carbon atoms in the branched chain is one or two. On the other hand, a preferred second option for the number of branched carbon atoms in the branched chain is three or more, which can be set to 3 to 10, preferably 3 to 8, and more preferably 4 to 7.

[0110] Can be used as R 2 The hydrocarbon group is not particularly limited as long as the total number of carbon atoms constituting it (referred to as the carbon number) is 8 or more. However, from the viewpoint of achieving a higher level of selectivity and durability of the metal extractant, 9 to 20 is preferred. From the viewpoint of the selectivity and durability of the metal extractant, it can be used as R2 The preferred first embodiment of the hydrocarbon group has 8 to 11 carbon atoms, more preferably 8 to 10, and particularly preferably 8 or 9. On the other hand, from the viewpoint of maintaining high selectivity of the metal extractant while further improving durability, it can be used as R... 2 The preferred second embodiment of the hydrocarbon group is a carbon number of 10 to 24, and even more preferably 12 to 20.

[0111] R in the above-mentioned linker L C When the hydrocarbon group is removed, R 2 It can be the same as or different from the hydrocarbon group.

[0112] The case where the compound represented by formula (II) is a nonpolymeric compound is the same as the case where the compound represented by formula (I) or formula (IC).

[0113] Compounds represented by formula (II) or formula (IIC) are able to convert R in the formula 1 L, R 2 And α are appropriately combined to form, preferably by combining preferred symbols of each symbol with each other.

[0114] However, compounds represented by formula (II) or (IIC), like compounds represented by formula (I) or (IC), preferably have at least one active hydrogen atom. The active hydrogen atom can be present in R. 1 L, R 2 and in any of the rings formed by α, but preferably in R 1 Or in L. The number of hydroxyl groups present in the compound is the same as that in the compound represented by formula (I) or formula (IC).

[0115] In compounds represented by formula (II) or formula (IIC), -OR 1 base and -LR 2 The bonding position on the benzene ring is not particularly limited, and it can be related to the -OR in compounds represented by formula (I) or formula (IC). 1 The group and X are bonded to the same position on the benzene ring.

[0116] Furthermore, in the compound represented by formula (IIC), the position where the α-shaped ring bonds to the benzene ring is not particularly limited, and is the same as the position where the α-shaped ring bonds to the benzene ring in the compound represented by formula (I) or formula (IC).

[0117] The compounds of the present invention (including compounds represented by formula (II) above) preferably have functional groups selected from the functional group group G below. This functional group, as a coordination functional group that coordinates with the metal ion targeted for extraction, preferably contributes to improving the selectivity and durability of the metal extractant containing the compound of the present invention.

[0118] The compounds of the present invention do not have any particular limitation on the position of the functional groups introduced or bonded, as long as they have the following functional groups within the molecule. For example, they can be bonded to the benzene ring in each formula, or to a ring formed by any atomic group α, and can be used as R. 1 Import or import into R 1 In this invention, from the viewpoint of achieving a higher level of both selectivity and durability of the metal extractant, it is preferable to introduce or incorporate it into X as X of formula (I) or formula (IC), or as -LR of formula (II) or formula (IIC). 2 Import.

[0119] From the viewpoint of achieving a higher level of selectivity and durability of metal extractants, the functional groups of the compounds of the present invention are preferably phosphate groups or phosphonic acid groups in functional group G, and more preferably X as described below. A X B Both Z and φ are phosphate or phosphine groups with oxygen atoms.

[0120] <Functional Group G>

[0121] Carboxyl group, phosphate group, phosphonic acid group, hypophosphonic acid group, sulfonic acid group (-S(=O)2OR) C ), sulfinic acid group (-S(=O)OR) C )

[0122] Phosphate, phosphonate, and hypophosphonate groups are usually represented by -OP (=O)(OR) C )2、-P(=O)(OR C )2 or -P(=O)(OR C )R D However, the phosphate group, phosphonate group, and hypophosphonate group used as functional groups in this invention refer to groups composed of -X A -P(=Z)(X B R C )2、-P(=Z)(X B R C )2 or -P(=Z)(X B R C )R D The group indicated. Here, X A Represents an oxygen atom or a sulfur atom, preferably an oxygen atom, X BZ represents an oxygen atom or a sulfur atom, preferably an oxygen atom. X in each group... A X B There are no particular restrictions on the combination of X and Z; any appropriate combination is permissible. Among the phosphate group, phosphonic acid group, and hypophosphonic acid group, X is particularly preferred. A X B Both Z and are oxygen atoms.

[0123] In this invention, R in the functional group C and R D These represent hydrogen atoms or substituents, respectively. As can be used as R... C and R D The substituents are not particularly limited; for example, groups selected from substituents Z described later can be cited. Among them, [the substituent] can be used as R. C and R D From the viewpoint of solubility in the oil phase, alkyl, alkenyl, alkynyl, aryl, and aralkyl substituents are preferred. These can be used as R... C and R D The hydrocarbon group is not particularly limited, but it is preferred to be an R group that can be used in the above formula (II). 2 The hydrocarbon group is the same, and more preferably an alkyl group.

[0124] The two R groups of the phosphate group and the phosphonate group respectively C They can be the same or different. In two Rs... C Under different circumstances, one R is preferred. C For hydrogen atoms, the other R is preferred. C It is a hydrocarbon group. Furthermore, the above functional group is -LR in formula (II) or formula (IIC). 2 When a group is introduced, and the phosphate group and phosphonate group have one hydrocarbon group, that hydrocarbon group is interpreted as the aforementioned R. 2 Furthermore, preferably, the R-value of phosphatic acid is... C For hydrogen atoms, R D It is a hydrocarbon group.

[0125] Carboxyl groups can form salts, and in R C When a hydrogen atom is removed, phosphate, phosphonic acid, sulfonic acid, hypophosphonic acid, and sulfinic acid groups can form salts. There are no particular limitations on the cations that can form salts; for example, metal cations, especially metal cations from Group 1 or Group 2, can be included.

[0126] As 2 R C and R C and R D The preferred first method is that, in each functional group, 1 R C For hydrogen atoms, the remaining R C or R DThis is achieved by using substituents (to create acidic functional groups). In this method, each functional group has one hydroxyl group, acting as R. 1 It can also use monovalent substituents. On the other hand, as two R... C and R C and R D The preferred second approach is that, in each functional group, all R... C and R D Both methods employ substituents. In this method, the two substituents can be the same or different, but preferably both are hydrocarbon groups. In this second method, none of the functional groups contain a hydroxyl group, which serves as R. 1 Use hydrogen atoms or metallic elements.

[0127] The compounds of the present invention may have at least one functional group selected from the functional group G mentioned above, or they may have two or more functional groups.

[0128] From the viewpoint of being able to balance the selectivity and durability of metal extractants at a higher level, the compounds of the present invention preferably have hydrocarbon groups having 9 or more carbon atoms.

[0129] For compounds of the present invention having a hydrocarbon group having 9 or more carbon atoms, the position of the hydrocarbon group introduced or bonded is not particularly limited, as long as it has a hydrocarbon group having 9 or more carbon atoms. For example, it can be bonded to the benzene ring in each formula, or to a ring formed by any group α, and can be used as R. 1 Import or import into R 1 In this invention, from the viewpoint of achieving a higher level of selectivity and durability of the metal extractant, a hydrocarbon group having 9 or more carbon atoms is preferably introduced as X in formula (I) or formula (IC), or as -LR in formula (II) or formula (IIC). 2 The introduction is more preferably into a functional group selected from the above-mentioned functional group, and even more preferably into a functional group that has OR as a phosphate group and a phosphonate group. C R in C or the R of the phosphonic acid group D Import.

[0130] As hydrocarbon groups with 9 or more carbon atoms, examples of those that can be used as R 2 The hydrocarbon group has 9 or more carbon atoms.

[0131] The number of hydrocarbon groups with 9 or more carbon atoms in the compounds of the present invention is not particularly limited, and can be one or more, preferably one or two.

[0132] When the compound of the present invention has two hydrocarbon groups having 9 or more carbon atoms, a preferred first embodiment of the combination of these hydrocarbon groups is a combination of a hydrocarbon group having 12 or more carbon atoms and a hydrocarbon group having 8 to 11 carbon atoms. In this embodiment, the hydrocarbon group having 12 or more carbon atoms more preferably has 14 or more carbon atoms. There is no particular upper limit on the number of carbon atoms; for example, it is preferably 24 or less, more preferably 20 or less. A preferred second embodiment of the combination of these hydrocarbon groups is a combination of hydrocarbon groups having 12 or more carbon atoms. In this embodiment, the hydrocarbon group having 12 or more carbon atoms has the same number of carbon atoms as in the first embodiment described above.

[0133] Furthermore, in the second embodiment described above, the compounds of the present invention also include a method of changing two hydrocarbon groups with nine or more carbon atoms to hydrocarbon groups with eight to 11 carbon atoms (for convenience, this is referred to as the third embodiment).

[0134] On the other hand, in the first to third embodiments regarding the combination of two hydrocarbon groups in the compounds of the present invention, there is no particular limitation on the molecular structure of the hydrocarbon groups. However, from the viewpoint of the selectivity and durability of the metal extractant, a combination of hydrocarbon groups with branched structures is preferred, and a combination of alkyl groups with branched structures is more preferred. Furthermore, in the above embodiments, there is no particular limitation on the type of hydrocarbon groups; the same type of substituents can be combined, as can different types of substituents. From the viewpoint of the selectivity and durability of the metal extractant, a combination of alkyl groups is preferred as a combination of the same substituents.

[0135] The compounds of the present invention can act as monodentate ligands for specific metal ions present in the aqueous phase (the metal ions to be extracted), but from the viewpoint of selectivity and durability, they are preferably acted as polydentate ligands.

[0136] The molecular weight of the compounds of the present invention is not particularly limited, and for example, it can be set to 150 to 50,000. From the viewpoint of solubility in the oil phase, it is preferably 200 to 10,000, and more preferably 250 to 1,000. In the present invention, when the polymer chain of the present invention is present, the molecular weight, unless otherwise specified, refers to the number-average molecular weight converted from standard polystyrene based on gel permeation chromatography (GPC).

[0137] -Measurement of molecular weight-

[0138] The method for determining the molecular weight of oligomers is generally set as the value determined by the method described in condition 1 or condition 2 (preferred). However, a suitable eluent can be selected and used according to the type of oligomer.

[0139] (Condition 1)

[0140] String: Connects 2 TOSOH TSKgel Super AWM-H (product name, manufactured by Tosoh Corporation)

[0141] Charge carriers: 10 mM LiBr / N-methylpyrrolidone

[0142] Temperature measured: 40℃

[0143] Carrier flow rate: 1.0 ml / min

[0144] Sample concentration: 0.1% by mass

[0145] Detector: RI (Refractive Index) Detector

[0146] (Condition 2)

[0147] Tube String: Use a tube string to connect TOSOH TSKgel Super HZM-H, TOSOH TSKgel Super HZ4000, and TOSOH TSKgel Super HZ2000 (all trade names, manufactured by Tosoh Corporation).

[0148] Support: Tetrahydrofuran

[0149] Temperature measured: 40℃

[0150] Carrier flow rate: 1.0 ml / min

[0151] Sample concentration: 0.1% by mass

[0152] Detector: RI (Refractive Index) Detector

[0153] The pKa of the compounds of the present invention is not particularly limited, and suitable values ​​can be adopted, preferably 1.0 to 14. For example, when the compounds of the present invention have an active hydrogen atom as the hydroxyl group bonded to the phosphorus atom in formula (I) or formula (IC)X or formula (II) or formula (IIC), the pKa becomes a small value, specifically, usually in the range of 2.0 to 7.5. On the other hand, the compounds of the present invention as R of various formulas 1 When hydrogen atoms are not present in X of formula (I) or formula (IC), or in L of formula (II) or formula (IIC), pKa becomes a larger value, specifically, usually in the range of 8.0 to 14. pKa can be determined by neutralization titration.

[0154] The compounds of the present invention may have substituents, and among the substituents that may be present, groups selected from the substituents GZ described below are examples (but excluding groups containing a nitrogen atom).

[0155] The compounds of the present invention can be synthesized with reference to known synthesis methods, synthesis methods described in the examples described below, etc.

[0156] As specific examples of compounds of the present invention, in addition to the compounds synthesized in the examples, the following compounds may also be cited, but the present invention is not limited to these.

[0157] [Chemical Formula 6]

[0158]

[0159] -Substituent GZ-

[0160] The alkyl group (preferably an alkyl group with 1 to 20 carbon atoms, such as methyl, ethyl, isopropyl, tert-butyl, pentyl, heptyl, 1-ethylpentyl, benzyl, 2-ethoxyethyl, 1-carboxymethyl, etc.), alkenyl (preferably an alkenyl group with 2 to 20 carbon atoms, such as vinyl, allyl, oleyl, etc.), alkynyl (preferably an alkynyl group with 2 to 20 carbon atoms, such as ethynyl, butyrynyl, phenylethynyl, etc.), cycloalkyl (preferably a cycloalkyl group with 3 to 20 carbon atoms, such as cyclopropyl, cyclopentyl, cyclohexyl, 4-methylcyclohexyl, etc.). When referred to as alkyl in this invention, it generally means... It includes cycloalkyl groups, but is described separately here. Aryl groups (preferably aryl groups with 6 to 26 carbon atoms, such as phenyl, 1-naphthyl, 4-methoxyphenyl, 2-chlorophenyl, 3-methylphenyl, etc.), aralkyl groups (preferably aralkyl groups with 7 to 23 carbon atoms, such as benzyl, phenethyl, etc.), and heterocyclic groups (preferably heterocyclic groups with 2 to 20 carbon atoms, more preferably heterocyclic groups having at least one oxygen atom, sulfur atom, and nitrogen atom in a 5 or 6-membered ring). Heterocyclic groups include aromatic heterocyclic groups and aliphatic heterocyclic groups. Examples include tetrahydropyranyl, tetrahydrofuranyl, 2-pyridyl, and 4-pyridyl. The following groups are listed: 2-imidazolyl, 2-benzimidazolyl, 2-thiazolyl, 2-oxazolyl, pyrrolidone, etc.; alkoxy groups (preferably alkoxy groups with 1 to 20 carbon atoms, such as methoxy, ethoxy, isopropoxy, benzyloxy, etc.); aryloxy groups (preferably aryloxy groups with 7 to 26 carbon atoms, such as phenoxy, 1-naphthoxy, 3-methylphenoxy, 4-methoxyphenoxy, etc.); heterocyclic oxy groups (groups with -O- groups bonded to the above heterocyclic groups); alkoxycarbonyl groups (preferably alkoxycarbonyl groups with 2 to 20 carbon atoms, such as ethoxycarbonyl, 2-ethylhexyloxycarbonyl, dodecane, etc.). Oxycarbonyl, etc.), aryloxycarbonyl (preferably aryloxycarbonyl with 6 to 26 carbon atoms, such as phenoxycarbonyl, 1-naphthoxycarbonyl, 3-methylphenoxycarbonyl, 4-methoxyphenoxycarbonyl, etc.), heterocyclic oxycarbonyl (a group with -O-CO- group bonded to the above heterocyclic group), amino (preferably amino, alkylamino, arylamino containing 0 to 20 carbon atoms, such as amino(-NH2), N,N-dimethylamino, N,N-diethylamino, N-ethylamino, aniline, etc.), aminosulfonyl (preferably aminosulfonyl with 0 to 20 carbon atoms, such as N,N-dimethylaminosulfonyl, N-phenylaminosulfonyl, etc.), acyl groups (including alkyl carbonyl, alkenyl carbonyl, alkynyl carbonyl, aryl carbonyl, heterocyclic carbonyl, preferably acyl groups with 1 to 20 carbon atoms, such as acetyl, propionyl, butyryl, octanoyl, hexadecanoyl, acryl, methacryl, crotonyl, benzoyl, naphthoyl, nicotinyl, etc.), acyloxy groups (including alkyl carbonyloxy, alkenyl carbonyloxy, alkynyl carbonyloxy, heterocyclic carbonyloxy, preferably acyloxy groups with 1 to 20 carbon atoms, such as acetyloxy, propionyloxy, butyryloxy, octanoyloxy, hexadecanoyl, etc.), Acryloyloxy, methacryloyloxy, crotonyloxy, nicotinoxy, etc.), aromatic acryloyloxy (preferably aromatic acryloyloxy with 7 to 23 carbon atoms, such as benzoyloxy, naphthyloxy, etc.), carbamoyl (preferably carbamoyl with 1 to 20 carbon atoms, such as N,N-dimethylcarbamoyl, N-phenylcarbamoyl, etc.), amide (preferably amide with 1 to 20 carbon atoms, such as acetamido, benzoylamino, etc.), alkylthio (preferably alkylthio with 1 to 20 carbon atoms, such as methylthio, ethylthio, isopropylthio, benzylthio, etc.) Arylthioyl (preferably arylthioyl with 6 to 26 carbon atoms, such as phenylthioyl, 1-naphthioyl, 3-methylphenylthioyl, 4-methoxyphenylthioyl, etc.), heterocyclic thioyl (a group with -S- group bonded to the above heterocyclic group), alkylsulfonyl (preferably alkylsulfonyl with 1 to 20 carbon atoms, such as methylsulfonyl, ethylsulfonyl, etc.), arylsulfonyl (preferably arylsulfonyl with 6 to 22 carbon atoms, such as benzenesulfonyl, etc.), alkylsilyl (preferably alkylsilyl with 1 to 20 carbon atoms, such as monomethylsilyl, dimethylsilyl, trimethylsilyl, etc.). alkylsilyl, triethylsilyl, etc.), arylsilyl (preferably arylsilyl with 6 to 42 carbon atoms, such as triphenylsilyl), alkoxysilyl (preferably alkoxysilyl with 1 to 20 carbon atoms, such as monomethoxysilyl, dimethoxysilyl, trimethoxysilyl, triethoxysilyl, etc.), aryloxysilyl (preferably aryloxysilyl with 6 to 42 carbon atoms, such as triphenoxysilyl), phosphoryl (preferably phosphoric acid with 0 to 20 carbon atoms, such as -OP(=O)(R, P )2) Phosphonyl group (preferably a phosphonyl group with 0 to 20 carbon atoms, for example, -P(=O)(R P )2) Oxyphosphin group (preferably oxyphosphin group with 0 to 20 carbon atoms, for example, -P(R P 2) Phosphonic acid group (preferably a phosphonic acid group with 0 to 20 carbon atoms, for example, -PO(OR) P 2) Sulfonate (sulfonic acid group), carboxyl group, hydroxyl group, thioalkyl group, cyano group, halogen atom (e.g., fluorine atom, chlorine atom, bromine atom, iodine atom, etc.). R PIt is a hydrogen atom or a substituent (preferably a group selected from substituents G and Z).

[0161] Furthermore, each of the groups listed in these substituents GZ can be further replaced by the aforementioned substituents GZ.

[0162] The aforementioned alkyl, alkylene, alkenyl, alkenylene, ynyl and / or ynylene groups can be cyclic or chain-like, and can be straight-chain or branched.

[0163] Methods for the separation and recovery of metal ions

[0164] The metal ion separation and recovery method of the present invention (hereinafter, sometimes referred to as the separation and recovery method of the present invention) is a method of mixing an aqueous phase containing multiple metal ions and an oil phase containing the metal extractant of the present invention. This allows specific metal ions coordinated to the metal extractant of the present invention to move (extract) from the aqueous phase to the oil phase, and to be separated and recovered with high selectivity and high recovery rate. Furthermore, even when the metal extractant of the present invention has been used once and reused repeatedly, the specific metal ions can be separated and recovered with high selectivity and high recovery rate by suppressing the decrease in selectivity and recovery rate during initial use. Moreover, even when the metal extractant of the present invention is in contact with the aqueous phase for a long period of time, the specific metal ions can be separated and recovered with high selectivity and high recovery rate by suppressing the initial decrease in selectivity and recovery rate. In other words, even when the separation and recovery method of the present invention is repeatedly performed or continuously for a long time, it can extract specific metal ions present in the aqueous phase into the oil phase while suppressing the initial decrease in high selectivity and high recovery rate. Here, the metal ions extracted into the oil phase can be a portion of the multiple metal ions contained in the aqueous phase, or all types of heterometallic ions contained in the aqueous phase.

[0165] Even when repeatedly performed or continuously for a long time, the separation and recovery method of the present invention can selectively and efficiently extract one type of metal ion as a valuable metal element into the oil phase. It can also selectively and efficiently extract one type of metal ion from two or more different groups of metal ions, for example, those belonging to Groups 1 to 14 of the periodic table. In particular, even when repeatedly performed or continuously for a long time, the separation and recovery method of the present invention can selectively and efficiently extract one type of metal ion from two or more different groups of metal ions belonging to Groups 8 to 12 of the periodic table, especially preferably one type of metal ion from the same period, namely cobalt and nickel ions, into the oil phase.

[0166] In the separation and recovery method of the present invention, the metal extractant of the present invention extracts two or more metal ions from a group of multiple metal ions present in the aqueous phase into the oil phase in the wet extraction method. However, it has been found that it has the characteristics and functions of extracting one metal ion with high selectivity and high recovery rate for a long time, and is suitable for the new application of separating and recovering two or more metal ions, especially heterogeneous metal ions.

[0167] <Water Phase>

[0168] There are no particular restrictions on the type of water used to form the aqueous phase, but (ultra)pure water, ion-exchanged water, etc., can be used.

[0169] The aqueous phase may contain at least two metal ions belonging to Groups 1 to 14 of the periodic table, preferably at least two metal ions belonging to Groups 3 to 14, and may also contain metal ions belonging to Groups 15 to 17.

[0170] In this invention, it is preferable to include two or more metal ions belonging to Groups 1 to 14, more preferably two or more metal ions belonging to Groups 3 to 14, and even more preferably ions containing at least one transition metal element (a metal element belonging to Groups 3 to 12). In the case of including at least one transition metal element, it is preferable to include two or more metal ions belonging to Groups 4 to 12, more preferably two or more metal ions belonging to Groups 4 to 10, even more preferably two or more metal ions belonging to Groups 8 to 12, particularly preferably two or more metal ions belonging to Groups 9 to 12, and most preferably two or more metal ions belonging to both Groups 9 and 10. There are no particular limitations on the groups of the metal ions, but metal ions belonging to Periods 4 to 6 of the periodic table are preferred, more preferably metal ions belonging to Period 4 or 5. Furthermore, there is no particular limitation on the number of metal ions as long as there are two or more types. For example, it can be set to 2 to 15 types, preferably 2 to 8 types, and more preferably 2 to 5 types.

[0171] There are no particular restrictions on the combination of multiple metal ions. For example, combinations of groups can be made, such as combinations of groups 9 and 10, groups 9 and 12, groups 4 and 9, groups 8 and 10, groups 7, 9 and 10, and groups 7, 8, 9 and 10.

[0172] In this invention, there may be two or more metal ions belonging to each group, but from the viewpoint of exhibiting high selectivity, one type is preferred.

[0173] Specific combinations of metal ions include, for example, combinations containing Co and Ni, combinations containing Co and Zn, combinations containing Fe and Ni, combinations containing Zr and Rh, combinations containing Mn, Co and Ni, and combinations with Mn, Fe, Co and Ni.

[0174] The aqueous phase may contain both metal ions from the same group and metal ions from different groups. The aqueous phase may contain two or more types of metal ions from different groups, preferably two to four, and more preferably two.

[0175] There are no particular restrictions on which group a metallic element belongs to; appropriate atoms can be used. For example,

[0176] As metallic elements belonging to Group 1, Li, Na, Rb, and Cs are preferred examples.

[0177] As metallic elements belonging to Group 2, Mg, Ca, Sr, and Ba are preferred examples.

[0178] As metallic elements belonging to Group 3, Sc and Y are preferred examples.

[0179] As metallic elements belonging to Group 4, Ti, Zr, and Hf are preferred examples.

[0180] V, Nb, and Ta are preferred examples of metal elements belonging to Group 5.

[0181] As metallic elements belonging to Group 6, Cr, Mo, and W are preferred examples.

[0182] Mn and Tc are preferred examples of metal elements belonging to Group 7.

[0183] As metallic elements belonging to Group 8, Fe, Ru, and Os are preferred examples.

[0184] Co, Rh, and Ir are preferred examples of metal elements belonging to Group 9.

[0185] Ni, Pd, and Pt are preferred examples of metal elements belonging to Group 10.

[0186] As metallic elements belonging to Group 11, Cu, Ag, and Au are preferred examples.

[0187] Zn, Cd, and Hg are preferred examples of metallic elements belonging to Group 12.

[0188] As metallic elements belonging to Group 13, Al, Ga, In, and Tl are preferred examples.

[0189] As metallic elements belonging to Group 14, Ga, Sn, and Pb are preferred examples.

[0190] Sb and Bi are preferred examples of metallic elements belonging to Group 15.

[0191] As a metallic element belonging to Group 16, there are no particular restrictions, but Te is a preferred example.

[0192] As various metal ions, they can be appropriately prepared, for example, using various metal salts (salts of inorganic acids such as nitric acid and sulfuric acid of typical elements, or salts of organic acids such as acetic acid), mixtures of mined metals (ions), recyclables from metal waste, metal recyclables from other wastes (such as those from spent batteries (LiB)), and mixtures thereof. Examples of metal recyclables from spent LiB include those based on known methods such as wet processing and electrolysis.

[0193] The total content of various metal ions in the aqueous phase is not particularly limited and can be appropriately set. For example, it can be set to 1,000 to 1,000,000 ppm by mass, preferably 1,000 to 100,000 ppm by mass, more preferably 1,000 to 80,000 ppm by mass, and even more preferably 2,000 to 30,000 ppm by mass.

[0194] There is no particular limitation on the total content of metal ions belonging to Groups 8 to 12. It can be set appropriately, for example, it can be set to 1,000 to 80,000 ppm by mass, preferably 1,000 to 60,000 ppm by mass, and more preferably 2,000 to 30,000 ppm by mass.

[0195] The total content of metal ions belonging to Groups 3 to 7 and Groups 13 to 16 is not particularly limited and can be set appropriately, but for example, it can be set to 1,000 to 60,000 ppm by mass, preferably 1,000 to 30,000 ppm by mass.

[0196] The content of metal ions belonging to each group is not particularly limited and can be appropriately set. For example, it can be set to 1,000 to 60,000 ppm by mass, preferably 1,000 to 50,000 ppm by mass, and more preferably 2,000 to 25,000 ppm by mass. In addition, when two or more metal ions belonging to each group are contained, the content of metal ions belonging to each group is the total content.

[0197] In this invention, when the aqueous phase contains metal ions from different groups, the content of metal ions belonging to a certain group can be more or less than the content of metal ions belonging to other groups. In the separation and recovery method of this invention, since metal ions can be separated and recovered multiple times with high selectivity and high recovery rate, it is not necessary to set the content of metal ions belonging to different groups at a specific ratio. For example, the mass ratio of the content of metal ions belonging to another group (e.g., metal ions other than those extracted at maximum extraction rate (including unextracted metal ions)) to the content of metal ions belonging to a specific group (e.g., metal ions extracted at maximum extraction rate) [content of metal ions belonging to a specific group: content of metal ions belonging to another group] can be set to, for example, 100:1 to 10,000, preferably 100:10 to 5,000, more preferably 100:50 to 1,000, and even more preferably 100:80 to 130.

[0198] There are no particular restrictions on the pH of the aqueous phase, and it can be set appropriately. However, if the solubility of metal ions and the formation of complex ions are taken into account, it is preferable to set it to 0.1 to 10, and more preferably to set it to 2.0 to 10.

[0199] The pH of the aqueous phase can be adjusted using acids or bases, for example. As an acid, known acids can be used without particular limitation, including inorganic acids such as sulfuric acid, hydrochloric acid, nitric acid, and phosphoric acid, as well as organic acids such as formic acid, acetic acid, oxalic acid, organic phosphoric acid, and organic sulfonic acid. As a base, known bases can be used without particular limitation, including inorganic bases and organic bases, with inorganic bases being preferred. Examples of inorganic bases include metal bases such as hydroxides and carbonates of Group 1 or Group 2 metals, and further examples include ammonia and ammonium chloride. Examples of organic bases include organic ammonium salts.

[0200] There are no particular restrictions on the temperature of the aqueous phase; for example, it can be set to 10–60°C.

[0201] The aqueous phase may contain ligands (compounds) that coordinate with metal ions or compounds that generate ligands, as needed.

[0202] The aqueous phase can be prepared by dissolving metal ions in water. There are no particular limitations on the preparation conditions. For example, the preparation temperature can be set between 10 and 60°C.

[0203] In addition to the metal ions mentioned above, the aqueous phase may also contain masking agents. Known masking agents can be used without particular limitation. Examples include monodentate ligands such as ammonia and chelating agents such as dithizone.

[0204] <Oil phase>

[0205] In the separation and recovery method of the present invention, an oil phase (organic phase) containing one or more metal extractants of the present invention is used on the aqueous phase. In the present invention, even metal extractants that have been recovered and purified after use (also called recovered products) and metal extractants used for a long time (collectively referred to as used products along with recovered products) can maintain the high selectivity and high recovery rate exhibited by unused metal extractants (also called unused products). Therefore, the metal extractants of the present invention contained in the oil phase can be unused products or used products, and both unused products and used products can be used simultaneously. Furthermore, there are no particular limitations on the mixing ratio when unused products and used products are used simultaneously, and it can be appropriately determined.

[0206] Furthermore, as described above, the metal extractant used in the separation and recovery method of the present invention may include other metal extractants, but preferably includes only the compounds of the present invention.

[0207] The metal extractant of the present invention exhibits its solubility in organic solvents and exists in the oil phase to coordinate and bond with metal ions present near the interface between the aqueous and oil phases, thereby demonstrating the function of moving the metal ions into the oil phase. In this invention, solubility relative to organic solvents refers to the property of the metal extractant to dissolve in an organic solvent at a concentration described later.

[0208] There are no particular limitations on the organic solvent used to form the oil phase; any suitable organic solvent can be used. Examples include alcohol solvents, ether solvents, hydrocarbon solvents (aromatic solvents, aliphatic solvents), and halogen solvents. Among these, hydrocarbon solvents are preferred, and various solvents that are fractionation components of petroleum are more preferred. Hydrocarbon solvents such as aromatics, paraffins, cycloalkanes, kerosene, gasoline, naphtha, kerosene, and light oils are even more preferred.

[0209] The content of the metal extractant in the oil phase is appropriately set considering factors such as the content of metal ions and the coordination amount with metal ions. For example, the content in the oil phase can be set to 20 to 10,000 mmol / L (mM), preferably 50 to 1,000 mmol / L, and more preferably 100 to 500 mmol / L.

[0210] There are no particular restrictions on the temperature of the oil phase; for example, it can be set to 10–60°C.

[0211] In addition to the acidic metal extractant of this invention, the oil phase may also contain appropriate components.

[0212] The oil phase can be prepared by dissolving the metal extractant in an organic solvent. There are no particular limitations on the preparation conditions of the oil phase; for example, the preparation temperature can be set to 10–60°C.

[0213] (Contact, Mixing)

[0214] In the separation and recovery method of the present invention, the above-mentioned aqueous phase and oil phase are mixed and allowed to stand.

[0215] There are no particular restrictions on the mixing and settling conditions at this time, and they can be set appropriately. For example, various mixing devices can be used for mixing. Examples of mixing devices include using a magnetic stirrer (stirrer tip), a mechanical stirrer, and a mixer. The mixing conditions (stirring speed, stirring time, etc.) are only required to mix the aqueous and oil phases (conditions for coordination bonding between the metal extractant and metal ions), and can be set appropriately based on the combination of metal ions and metal extractant, the mixing temperature, and the mixing device. For example, the stirring speed, such as the rotation speed of a magnetic stirrer, can be set to 80–200 rpm. The stirring time is not uniquely determined based on the mixing conditions, but can be set to, for example, 10 minutes to 24 hours. There are no particular restrictions on the mixing temperature, and it can be set to, for example, 10–60°C.

[0216] There are no particular restrictions on the settling conditions, as long as the aqueous and oil phases separate into two layers, and they can be set appropriately. In wet extraction, the settling time is typically set from 10 minutes to 24 hours after mixing stops. There are no particular restrictions on the settling temperature; for example, it can be set from 10 to 60°C.

[0217] In the mixing of the aqueous and oil phases, the mixing ratio of the aqueous and oil phases is appropriately set according to the content (concentration) of metal ions and the content (concentration) of the metal extractant, and is not uniquely determined. For example, when mixing aqueous and oil phases that meet the above-mentioned concentrations, the oil phase ratio can be set to 50 to 2,000 mL relative to 100 mL of aqueous phase, preferably 80 to 1,000 mL, and more preferably 80 to 200 mL. On the other hand, if the metal ions present in the aqueous phase are of interest, the oil phase is preferably mixed at a ratio of 0.5 to 20 moles of the metal extractant relative to the total content (moles) of metal ions, more preferably 0.5 to 10 moles of the metal extractant. Furthermore, the content of the metal extractant relative to the total content of metal ions that the metal extractant can coordinate with (also called the mixing amount; the ratio of the number of moles of metal extractant to the total number of moles of metal ions: molar ratio) can be set to, for example, 0.5 to 10.0 equivalents, preferably 0.5 to 6.0 equivalents. Here, the metal ions that can be coordinated by the metal extractant refer to the metal ions that are coordinated by the metal extractant and extracted into the oil phase.

[0218] In the mixing of the aqueous and oil phases, the pH of the mixture can also be adjusted. Here, the pH set for the specific metal ion being extracted is not unique, but rather appropriately determined considering factors such as the pKa of the metal extractant, the complexation constant between the metal extractant and the metal ion, and the coordination number of the metal ion. The pH of the mixture is preferably set to 0.01–14, for example, more preferably 0.1–10. From the viewpoint of selectivity and recovery, it is preferable to set the pH of the mixture according to the metal extractant used. For example, if the pKa of the metal extractant (the compound of the present invention) shows a low value, the pH of the mixture is preferably set to 0.5–9.0 within the aforementioned range, more preferably 1.0–8.5, and even more preferably 2.0–8.0. On the other hand, if the pKa of the metal extractant shows a large value, the pH of the mixture is preferably set to 5.0–12.0 within the aforementioned range, more preferably 7.0–12.0, and even more preferably 7.0–11.0.

[0219] pH can be prepared using the aforementioned acids or bases or their aqueous solutions, but the use of ammonia or ammonium salts is one of the preferred methods.

[0220] When adjusting the pH of the mixing system during the mixing of aqueous and oil phases, the mixing of the aqueous and oil phases and the subsequent settling are carried out after pH adjustment.

[0221] The two-phase separated fluid (solvent extraction phase, solvent extraction system) obtained by mixing the aqueous and oil phases and allowing them to stand exists in a layered phase separation state with the aqueous and oil phases in contact. Moreover, the metal ions coordinated and bonded by the metal extractant among the aforementioned metal ions exist (move) in the oil phase.

[0222] Ideally, the number of metal ions extracted into the oil phase is one, but sometimes it is two or more. In such cases, for example, it can be set to 2 to 10, preferably 2 to 6, and more preferably 2 or 3. There is no particular limitation on the number of metal ions extracted into the oil phase from a variety of metal ions. For example, it is preferable that they are the same as the two or more heterometallic ions (combinations) contained in the aqueous phase as described above.

[0223] The simple method of mixing the aqueous and oil phases and allowing them to stand in the separation and recovery method of the present invention enables long-term, highly selective, and high-recovery separation and extraction of specific metal ions from a variety of metal ions. In particular, it enables the long-term, highly selective, and high-recovery separation and recovery of one metal ion while extracting ions of two or more metal elements. Moreover, even when using a pre-used product as a metal extractant, the specific metal ion can be separated and recovered with the same or higher selectivity and recovery rate as an unused product.

[0224] The ability to selectively and efficiently separate and recover a single metal ion is not uniquely determined by its group or period, content, or the type of metal extractant. For example, when extracting both Group 9 and Group 10 metal ions into the oil phase, Group 9 metal ions can be separated and recovered with high selectivity and high recovery. In particular, when extracting Co ions as Group 9 and Ni ions as Group 10, Co ions can be separated and recovered with high selectivity and high recovery. Furthermore, when extracting both Group 9 and Group 12 metal ions into the oil phase, Group 12 metal ions can be separated and recovered with high selectivity and high recovery. Additionally, when extracting both Group 8 and Group 10 metal ions into the oil phase, Group 8 metal ions can be separated and recovered with high selectivity and high recovery.

[0225] As described above, the separation and recovery method of the present invention can selectively and efficiently extract one or more metal ions from a variety of metal ions present in an aqueous phase into an oil phase and recover them. In particular, the separation and recovery method of the present invention can simultaneously extract two or more metal ions and simultaneously recover one of those metal ions with high selectivity and high recovery rate. Therefore, by further providing the aqueous phase containing two or more metal ions obtained from back-extraction from the oil phase to the separation and recovery method of the present invention, the selectivity of one metal ion can be further improved without significantly impairing the recovery rate, resulting in the high recovery rate of high-purity metal ions. Moreover, even if this separation and recovery and back-extraction are performed repeatedly or continuously for a long period of time, the high selectivity and high recovery rate of the aforementioned metal ions will not be compromised, and the metal ions can still be extracted and recovered.

[0226] This separation and recovery method of the present invention can also be called an extraction method for two or more metal ions.

[0227] In the separation and recovery method of the present invention, the metal extractant can independently coordinate with a metal ion to extract the metal ion into the oil phase. Therefore, the aqueous phase and the oil phase may not contain compounds that coordinate with the metal ion or compounds that generate ligands, or other compounds that synergistically act with the metal extractant of the present invention to extract the metal ion, such as known metal extractants. In the separation and recovery method of the present invention, an aqueous phase containing a specific metal ion as an essential component and an oil phase containing the metal extractant of the present invention as an essential component are typically used.

[0228] The separation and recovery method of the present invention can include steps other than the step of mixing the aqueous phase and oil phase and allowing them to stand. Examples include steps such as pre-mixing the aqueous phase and oil phase before adjusting the pH, back-extracting (separating) metal ions from the oil phase obtained in the step of mixing the aqueous and oil phases and allowing them to stand (a step of back-extracting metal ions from the oil phase and recovering the metal extractant), recovering the back-extracted metal ions as a compound (salt), purifying the back-extracted metal ions or their compounds, purifying the recovered metal extractant, and pre-removing ions belonging to Group 1 or Group 2 of the periodic table. As a method for back-extracting (separating) metal ions from the oil phase, known methods can be used without particular limitation. For example, the liquid phase can be acidified, for example, at pH 2 to 4, by using inorganic acids such as sulfuric acid, hydrochloric acid, or nitric acid. Thus, by back-extracting metal ions from the oil phase, the oil phase containing the metal extractant can be recovered. As a method for recovering the back-extracted metal ions as a compound, known methods can be used without particular limitation.

[0229] In addition to the method using the metal extractant (unused product) of the present invention, the separation and recovery method of the present invention also includes a method using the metal extractant (used product) recovered in the above-mentioned recovery step alone or together with the unused product, and a method using the oil phase (containing the recovered metal extractant) obtained in the above-mentioned reverse extraction step (and contacting it with a newly prepared aqueous phase), etc.

[0230] The separation and recovery method of the present invention can be carried out through intermittent processing or through continuous processing.

[0231] In this invention, the metal extractant exhibits high durability, thus allowing for repeated processing, for example in batch processes, by using an untreated aqueous phase and recovered metal extractant (oil phase) to increase the number of treatments (number of contacts between the aqueous and oil phases). As mentioned above, the number of repeatable treatments cannot be uniquely determined based on contact conditions, metal ion concentration, etc.; for example, it can be set to 5 or more within the range satisfying the aforementioned selection ratio and extraction rate.

[0232] As a separation and recovery method involving repeated separation and recovery through intermittent processing, there are no particular limitations as long as the recovered metal extractant (used product) is used. For example, a method can be described as follows: First, a first separation and recovery method is performed using the metal extractant (unused product) of the present invention. Then, a second separation and recovery method is performed, in which the oil phase recovered by the first separation and recovery method (containing the metal extractant used by the present invention) is contacted and mixed with an unused aqueous phase. The third and subsequent separation and recovery methods are then performed in the same manner as the second separation and recovery method. Specifically, the method described in the examples can be cited. The oil phase recovered in each separation and recovery method can also be appropriately purified. For example, a method can be used to remove metal ions mixed in the oil phase by contacting them with an aqueous solvent. Furthermore, the conditions in the first and subsequent separation and recovery methods are as described above.

[0233] On the other hand, in continuous processing methods, for example, the contact time between the aqueous phase and the oil phase (the contact time between the oil phase and the flowing aqueous phase) can be set to be relatively long. As mentioned above, the contact time cannot be uniquely determined based on contact conditions, metal ion concentration, or the flow rate of the aqueous phase, but it can be set to 12 hours or more, for example, within the range that satisfies the aforementioned selectivity and extraction rate. Furthermore, in continuous processing, the amount of flowing aqueous phase used can also be set to be greater than the aforementioned mixing ratio of the aqueous layer and the oil phase.

[0234] There are no particular limitations on the apparatus used to implement the separation and recovery method of the present invention, and known equipment can be used. For example, a separating funnel or a mixing sedimentation device can be used. Furthermore, contact and mixing devices that utilize a liquid delivery device, such as a flow synthesis device or an emulsion flow device, can also be used. The contact, mixing, and settling conditions in continuous processing can be applied according to the above-mentioned conditions.

[0235] Example

[0236] The present invention will now be described in further detail with reference to embodiments, but the explanation of the present invention is not limited thereto.

[0237] In the following examples, the terms "parts" and "%" of composition are based on mass unless otherwise stated. In this invention, "room temperature" means 25°C.

[0238] [Synthesis and preparation of compounds]

[0239] The compounds shown below were synthesized or prepared.

[0240] Furthermore, the following compounds are described: compound E-3 (octyl salicylate) is a commercially available product manufactured by Tokyo Chemical Industry Co., Ltd.; compound E-5 (2-butoxybenzoic acid) is a commercially available product manufactured by Chem-Bridge. Compound T-1 (5-nonylsalicylic oxime) is a commercially available product manufactured by ACORGAM5640 (trade name, manufactured by Solvay SA); compound T-2 (7-(4-ethyl-2-methyloctyl)-8-quinolinol) is a commercially available product manufactured by KELEX-100 (trade name, manufactured by Nordmann); and compound T-3 (4-nonylphenol) is a commercially available product manufactured by FUJIFILM Wako PureChemical Corporation.

[0241] [Chemical Formula 7]

[0242]

[0243] <Synthesis of Compound E-1>

[0244] Compound E-1 was synthesized as follows.

[0245] Specifically, 15.1 g of N-chlorosuccinimide (FUJIFILM Wako Pure Chemical Corporation) and 230 g of toluene (FUJIFILM Wako Pure Chemical Corporation) were added to a 500 mL three-necked flask, and the mixture was stirred at room temperature. The N-chlorosuccinimide remained undissolved, dispersed in the toluene. While the flask was chilled, 30.0 g of bis(2-ethylhexyl) phosphite (Aldrich) was slowly added dropwise. After the addition was complete, the reaction mixture was brought to room temperature and stirred for 5 hours. The resulting reaction mixture was filtered to remove insoluble matter, and the solvent was distilled under reduced pressure. Hexane was added as needed, and the mixture was repeatedly filtered and distilled under reduced pressure to obtain 31.2 g (97% yield) of a pale yellow liquid (intermediate E1).

[0246] Next, 8.3 g of phenol (manufactured by FUJIFILM Wako Pure Chemical Corporation) and 105 g of toluene were added to a 300 mL three-necked flask, and the mixture was stirred at room temperature. To the resulting solution, 19.1 g of pyridine (manufactured by FUJIFILM Wako Pure Chemical Corporation), 9.8 g of 4-dimethylaminopyridine (manufactured by Tokyo Chemical Industry Co., Ltd.), and the pale yellow liquid obtained in the previous step (intermediate E1) were added, and the mixture was stirred at 60 °C for 12 hours. Water was added to the resulting reaction solution, and the organic matter was extracted with hexane. The hexane solution was washed with saturated sodium bicarbonate solution and water, and the solvent was distilled under reduced pressure. The crude product was subjected to silica gel chromatography (elution: hexane), yielding 16.9 g of a colorless, transparent liquid (intermediate E2).

[0247] Next, 40.0 g of tetrahydrofuran (super-dehydrated, FUJIFILM Wako PureChemical Corporation) was added to a 500 mL three-necked flask and cooled to -78 °C using an acetone / dry ice bath. 64 mL of a 1.0 M hexane solution of lithium diisopropylamine (Aldrich) was added dropwise, and the mixture was stirred for 30 minutes. Then, a solution consisting of 16.9 g of the colorless, transparent liquid (intermediate E2) obtained in the previous step and 55.3 g of tetrahydrofuran was added dropwise while maintaining the reaction mixture temperature below -50 °C. After the addition was complete, the mixture was stirred for 1 hour, then the reaction mixture was set to 0 °C and stirred for 5 hours. 100 mL of saturated ammonium chloride solution was added, and the mixture was extracted with ethyl acetate. The solvent was then distilled under reduced pressure to obtain the crude product. The crude product was subjected to silica gel chromatography (elution: hexane) to obtain 20.7 g of compound E-1 (65% yield, 2 steps).

[0248] The following describes the identification of compound E-1, which was synthesized in this manner.

[0249] That is, compound E-1 is dissolved in deuterated chloroform and the concentration is determined. 1 H-NMR (device: BLUKER400), the obtained graphs are shown in... Figure 1 .

[0250] δ (ppm): 10.28 (1H, br s, OH), 7.43 (1H, t, J = 7.1Hz), 7.34 (1H, ddd, J = 14.2, 7.7, 1.7Hz), 6.97 (1H, t, J = 7.7Hz), 6.91 ( 1H, ddd, J=14.1, 7.4, 1.7Hz), 4.05-3.82 (4H, m, OCH2-), 1.60-1.16 (18H, m), 0.90-0.82 (12H, m)

[0251] Based on the above, the obtained compound was identified as having the structure shown in E-1 above.

[0252] <Synthesis of Compound E-2>

[0253] Compound E-2 was synthesized as follows.

[0254] Specifically, 18.1 g of compound E-1, 130 g of 2-ethylhexanol (manufactured by FUJIFILM Wako Pure Chemical Corporation), and 3.5 g of sodium hydroxide (manufactured by FUJIFILM Wako Pure Chemical Corporation) were added to a 500 mL three-necked flask. After stirring at room temperature, the reaction solution was heated to 160 °C and stirred for 12 hours. 150 g of purified water was added to the resulting reaction solution, and the mixture was stirred for 20 minutes. After washing the solution with toluene, 4 M hydrochloric acid was added to the aqueous layer until the pH reached above 2. Then, toluene extraction was performed, and the solvent was distilled under reduced pressure to obtain 11.1 g of compound E-2 (yield 89%).

[0255] <Synthesis of Compound E-4>

[0256] Compound E-4 was synthesized as follows.

[0257] Specifically, 15.5 g of compound E-1, 10.2 g of butyl bromide (manufactured by Tokyo Chemical Industry Co., Ltd.), and 200 g of dimethylformamide (manufactured by FUJIFILM Wako Pure Chemical Corporation) were added to a 500 mL three-necked flask. After stirring at room temperature, the mixture was chilled. 15.5 g of potassium carbonate (manufactured by FUJIFILM Wako Pure Chemical Corporation) was added, and the mixture was stirred at 40 °C for 7 hours. The resulting reaction solution was poured into a 3 L Erlenmeyer flask containing 1.5 L of ice water and stirred at room temperature for 1 hour. The resulting solution was extracted with hexane, and the solvent was distilled under reduced pressure to obtain 15.4 g of the phenol-butylated compound E-1 (yield 91%).

[0258] The obtained compound was hydrolyzed under the same conditions as the hydrolysis reaction in the synthesis of compound E-2, thereby yielding 9.9 g (yield 88%) of compound E-4.

[0259] <Synthesis of Compound E-6>

[0260] In the synthesis of compound E-1, 2-butyl-1-n-octanol was used instead of 2-ethylhexanol. Otherwise, compound E-6 was synthesized in the same manner as compound E-1.

[0261] Preparation of aqueous solutions containing metal ions

[0262] 47.7 g of cobalt(II) sulfate heptahydrate (manufactured by FUJIFILM Wako Pure Chemical Corporation) and 52.6 g of nickel(II) sulfate heptahydrate (manufactured by FUJIFILM Wako Pure Chemical Corporation) were added to a 1 L volumetric flask, dissolved in ultrapure water, and stirred at 40 °C to prepare an aqueous solution (W1) containing metal ions.

[0263] Furthermore, the combination of metal ions shown in the "Metal ion concentration in aqueous phase before extraction (ppm)" column of Table 1-1 was changed to the amount of metal ion concentration recorded in the same column, and each sulfate was dissolved in ultrapure water, thereby preparing aqueous solutions (W2) and (W3) containing metal ions respectively.

[0264] The following shows the pH results of the prepared aqueous solutions (W1) to (W3) containing metal ions, measured using a pH meter (SK-620pHII, manufactured by SATOTECH).

[0265] Aqueous solution containing metal ions (W1): 6.5

[0266] Aqueous solution containing metal ions (W2): 7.0

[0267] Aqueous solution containing metal ions (W3): 6.2

[0268] <Preparation of Metal Extractant Solution (Oil Phase)>

[0269] Each of the synthesized or prepared compounds (all unused products) was added to a 100 mL volumetric flask and diluted to volume using IPsolvent 2835 (a paraffin solvent, manufactured by Idemitsu Kosan Co., Ltd.) at room temperature, thereby preparing metal extractant solutions (Y1) to (Y6) and (Yc1) to (Yc3) (concentration 350 mM) containing each compound as a metal extractant.

[0270] [Example 1]

[0271] As described below, the separation and extraction of metal ions was repeatedly performed 10 times using an aqueous solution (W1) containing metal ions and an oil layer (Y1) (wet extraction method).

[0272] In a 30 mL vial, 10 mL of the prepared aqueous solution (W1) containing metal ions was added to 10 mL of the extractant solution (Y1), and the mixture was stirred at 25°C for 30 minutes using a stirrer tip (premixing). At this point, the mixed amount (in equivalents) of compound E-1 relative to the total content of the coordinateable metal ions (with the same meaning as the extracted metal ions, Co and Ni in Example 1) was 0.98. Then, 10 M sodium hydroxide aqueous solution or 10 M hydrochloric acid was added to adjust the pH of the mixture to the value shown in the "pH at Mixing" column of Table 1-1. After further stirring at 25°C for 30 minutes, the mixture was allowed to stand at the same temperature for 1 hour. After confirming separation into two layers, an organic phase (oil phase) and an aqueous phase, liquid-liquid extraction was performed. The aqueous phase was removed for the separation and recovery of metal ions, and the oil phase was removed for the recovery of the metal extractant.

[0273] In addition, the pH of the mixture was measured using a pH meter (SK-620pHII, manufactured by SATOTECH).

[0274] Thus, the first (first) separation and extraction operation is performed, and the extracted metal ions are shown in the "Type" column of "Extracted Metal Ions" in Table 1-1. The metal ions extracted with the maximum extraction amount are shown in the "Maximum Extracted Ions" column of the same column in Table 1-1.

[0275] Next, in the initial separation and extraction operation described above, 10 mL of purified water and 10 M hydrochloric acid were added to 10 mL of the separated oil phase to adjust the pH of the mixture to 1.0. After stirring at room temperature for 30 minutes, the mixture was allowed to stand at the same temperature for 1 hour. This confirmed the separation into two layers: an organic phase (oil phase) and an aqueous phase. The oil phase was then separated and purified by liquid-liquid extraction, thus recovering the metal extractant and retrieving the oil phase.

[0276] Using the recovered oil phase (containing the recovered metal extractant), a second separation and extraction operation was performed in the same manner as the first separation and extraction operation described above (this time the mixing volume was set to 0.98 equivalents). The oil phase recovered in the second separation and extraction operation was then processed in the same way as described above to separate, purify, and recover the metal extractant.

[0277] The second separation and extraction operation and the metal extractant separation and purification operation were repeated 8 times, for a total of 10 times (the mixing volume was set to 0.98 equivalents each time). In addition, if the amount of organic solvent in the recovered oil phase was insufficient, IP Solvent 2835 was added to adjust the solution volume to 10 mL.

[0278] <Examples 2-8 and Comparative Examples 1-3>

[0279] In Example 1, the aqueous solution containing metal ions and the extractant solution were changed to the combination shown in the "Aqueous Phase" column and "Oil Phase" column of Table 1-1, and the pH when mixing the aqueous phase and the oil phase was set to the value shown in the "pH at Mixing" column of Table 1-1. Otherwise, the metal ion separation and extraction operations of Examples 2-8 and Comparative Examples 1-3 were repeated 10 times in the same manner as in Example 1.

[0280] The metal ions extracted in each embodiment are shown in the “Type” column of the “Extracted Metal Ions” column in Table 1-1, and the metal ions extracted at the maximum extraction amount are shown in the “Maximum Extracted Ions” column of the same column in Table 1-1.

[0281] In each embodiment and comparative example, the dissolved metal ion content was quantified using an inductively coupled plasma optical emission spectrometry (ICP-OES) apparatus (Optima 7300D (trade name), manufactured by PerkinElmer Co., Ltd.) for each prepared aqueous phase, each aqueous phase recovered in the first (1st) separation and extraction operation, and each aqueous phase recovered in the 10th separation and extraction operation. Furthermore, the comma in the metal ion concentration table indicates a decimal point, not a digit separator.

[0282] The measured values of the content of dissolved metal ions in each aqueous phase prepared in each example and comparative example are shown in the column of "Metal ion concentration (ppm) in the aqueous phase before extraction" in Table 1-1. Moreover, the measured values of the content of dissolved metal ions in each aqueous phase recovered in the first (1st) separation extraction operation in each example and comparative example are shown in the column of "Metal ion concentration (ppm) in the aqueous phase after the first extraction" in Table 1-2, and the measured values of the content of dissolved metal ions in each aqueous phase recovered in the 10th separation extraction operation in each example and comparative example are shown in the column of "Metal ion concentration (ppm) in the aqueous phase after 10 extractions" in Table 1-2.

[0283] <Evaluation 1: Evaluation of extraction rate (recovery rate)>

[0284] In each example and comparative example, based on the metal ion concentration CI in the prepared aqueous phase (aqueous phase before the 1st separation extraction operation) and the metal ion concentration C1 in the aqueous phase after the 1st separation extraction operation or the metal ion concentration C10 in the aqueous phase after the 10th separation extraction operation, the extraction rate (unit: %) of metal ions extracted with the maximum extraction amount was calculated by the following formula. The results are shown in the column of "First extraction rate" or "10th extraction rate" in Table 1-2, respectively.

[0285] In this experiment, the larger the value of each extraction rate, the more excellent the extraction ability (recovery ability) of specific metal ions in each separation extraction operation. Moreover, the smaller the difference between the first extraction rate and the 10th extraction rate (first extraction rate - 10th extraction rate), the more capable it is to maintain the high recovery rate shown by the unused metal extractant to recover specific metal ions even when the metal extractant is used repeatedly (even when the separation extraction operation is repeatedly carried out), and the metal extractant (compound used as the metal extractant) shows high durability.

[0286] In this experiment, the first extraction rate of 95% or more is qualified, and the 10th extraction rate of 70% or more is qualified.

[0287] First extraction rate (%) = [(CI - C1) / CI] × 100

[0288] 10th extraction rate (%) = [(CI - C10) / CI] × 100

[0289] <Evaluation 2: Evaluation of selectivity (separation ability)>

[0290] In each embodiment and comparative example, based on the metal ion concentration C1 in the aqueous phase before the first separation and extraction operation and the metal ion concentration C1 in the aqueous phase after the first separation and extraction operation or the metal ion concentration C10 in the aqueous phase after the tenth separation and extraction operation, the extraction amount (unit: ppm) of each metal ion is calculated according to the following formula. The selection ratio is calculated by dividing the extraction amount (ppm) of the metal ion extracted at the maximum extraction amount by the total extraction amount (CT) of the other metal ions. The results are shown in the "Initial Selection Ratio" column or the "Ten-Time Selection Ratio" column of Table 1-2.

[0291] In this experiment, the higher the value of each selectivity ratio, the better the selective extraction and recovery of specific metal ions relative to other metal ions in each separation and extraction operation (selectivity, separation ability). Furthermore, if the difference between the initial selectivity ratio and the 10-times selectivity ratio (initial selectivity ratio - 10-times selectivity ratio) is smaller, or if the 10-times selectivity ratio is larger than the initial selectivity ratio, it indicates that even with repeated use of the metal extractant (repeated separation and extraction operations), the high selectivity exhibited by the unused metal extractant can be maintained to selectively extract and recover specific metal ions. From the viewpoint of selectivity, the metal extractant (the compound used as the metal extractant) also exhibits high durability.

[0292] In this experiment, an initial selection ratio of 1.5 or higher is considered acceptable, and a selection ratio of 1.5 or higher after 10 selections is also considered acceptable.

[0293] Initial selection ratio = [(CI-C1) / CT] × 100

[0294] 10-selection ratio = [(CI-C10) / CT]×100

[0295] [Table 1-1]

[0296]

[0297] [Table 1-2]

[0298]

[0299] The following information can be gleaned from the results shown in Tables 1-1 and 1-2.

[0300] In the separation and recovery of metal ions based on wet extraction, Comparative Examples 1-3, which used conventional metal extractants T-1 to T-3, extracted only two metal ions present in the aqueous solution (W1) containing metal ions into the oil phase. However, in Comparative Example 3, which used metal extractant T-3, almost all of the Co ions (the metal ion with the maximum extraction amount) were extracted in the initial separation extraction operation, but a large amount of Ni was also extracted, resulting in a low initial selectivity. On the other hand, in Comparative Examples 1 and 2, which used metal extractants T-1 or T-2, the extraction rate after 10 extractions was significantly lower than the initial extraction rate. Based on these results, metal extractants T-1 to T-3 cannot simultaneously achieve high selectivity and durability, and cannot be repeatedly used in wet extraction.

[0301] In contrast, Examples 1 to 8, in which compounds E-1 to E-6 of the present invention were used as metal extractants, extracted two metal ions present in the aqueous solution containing metal ions into the oil phase. However, regarding the metal ions with the maximum extraction amount (Examples 1 to 6: Co ions, Example 7: Zn ions, Example 8: Fe ions), almost all of the metal ions were extracted in the initial separation extraction operation, and a high extraction rate of over 73% was maintained even in the 10th separation extraction operation. Moreover, in the 10th separation extraction operation in the initial separation extraction operation, the metal ions with the maximum extraction amount were extracted from the aqueous phase to the oil phase with a high selectivity relative to the metal ions other than the metal ions with the maximum extraction amount. Therefore, even if the compounds of the present invention are recovered after use in a wet extraction method and reused in multiple wet extraction methods, specific metal ions can be separated and recovered with high selectivity and high recovery rate by maintaining the selectivity and recovery rate at the time of initial use.

[0302] In addition, the concentration of metal ions in the water layer was reduced to 1 / 5. Otherwise, the experiment was conducted in the same manner as in Examples 1-7 and Comparative Examples 1-3, and the same results were obtained.

[0303] Thus, it is evident that even when repeatedly used as a metal extractant in wet extraction, the compounds of the present invention can selectively and efficiently separate and recover metal ions present in the aqueous phase. Furthermore, it is evident that among two or more metal ions belonging to different groups with similar physical and chemical behaviors, a specific metal ion can be selectively and efficiently separated and recovered, particularly one metal ion belonging to Groups 9 and 10 that can be recovered from waste LiB. The detailed reasons for the excellent properties exhibited by the compounds of the present invention are not yet clear, but it is believed that they are not easily decomposed or degraded even when exposed to the conditions of wet extraction.

[0304] Based on the above results, it can be seen that by back-extracting the oil phase obtained in the above embodiments under normal methods and conditions, regardless of the number of separation and extraction operations, metal ions extracted into the oil phase with high selectivity and high recovery rate can be separated and recovered simply and with high productivity without compromising high selectivity.

[0305] In techniques for recovering a specific metal ion from an aqueous phase containing multiple metal ions, it is often difficult to recover the specific metal ion with high selectivity and recovery rate. Maintaining high selectivity often results in a decrease in recovery rate, thus requiring multiple separation and recovery operations to achieve the desired recovery rate. In contrast, this invention demonstrates that even with prolonged use of metal extractants, it can extract one of two different metal ions from the aqueous phase with high selectivity and high recovery rate into the oil phase using a simple and highly productive method. Therefore, considering the ability to recover one metal ion with high recovery rate and further improved selectivity from the obtained oil phase through reverse extraction processes, while simultaneously reusing the metal extractant, with a simple and few steps and high productivity, the technical significance of this invention is substantial.

[0306] The invention and its methods have been described together, but unless specifically stated otherwise, it is not intended to limit the invention to any of the details described, and it is to be interpreted broadly without departing from the spirit of the invention as shown in the appended claims.

[0307] This application claims priority based on Japanese Patent Application 2023-050477, filed on March 27, 2023, the contents of which are incorporated herein by reference and are part of the description herein.

Claims

1. A metal extractant, which is used to extract metal ions present in an aqueous phase into an oil phase, wherein, The metal extractant has a structure represented by the following formula (I) and does not contain nitrogen atoms. [Chemical Formula 1] In equation (I), R 1 This indicates a hydrogen atom, a metal atom, or a monovalent substituent. X represents a monovalent substituent containing at least one of the following: oxygen, sulfur, and phosphorus atoms. The benzene ring in formula (I) can form a fused ring.

2. The metal extractant according to claim 1, wherein, The metal extractant has functional groups selected from the functional group G below. <Functional Group G> Carboxyl group, phosphate group, phosphonic acid group, hypophosphonic acid group, sulfonic acid group, sulfinic acid group.

3. The metal extractant according to claim 2, wherein, The functional groups selected from functional group G are phosphate groups or phosphonic acid groups.

4. The metal extractant according to claim 1, wherein, The metal extractant has a hydrocarbon group with 9 or more carbon atoms.

5. The metal extractant according to claim 3, wherein, The metal extractant has a hydrocarbon group with 9 or more carbon atoms.

6. The metal extractant according to claim 1, wherein, The metal extractant is represented by the following formula (II), [Chemical Formula 2] In equation (II), R 1 This indicates a hydrogen atom, a metal atom, or a monovalent substituent. L represents a divalent linker containing at least one of the following: oxygen, sulfur, and phosphorus atoms, but not a nitrogen atom. R 2 It represents a hydrocarbon group with 8 or more carbon atoms. However, when L is a carbonyl group, it represents a hydrocarbon group with 8 or more hydrogen atoms. The benzene ring in formula (II) can form a fused ring.

7. The metal extractant according to claim 1, wherein, The metal ions are ions of metal elements belonging to groups 1 to 14 of the periodic table.

8. The metal extractant according to claim 1, used for extracting and separating two or more metal ions belonging to different groups in the periodic table from the metal ions.

9. The metal extractant according to claim 6, used for extracting and separating two or more metal ions belonging to different groups in the periodic table from the metal ions.

10. A method for separating and recovering metal ions, comprising mixing an aqueous phase containing multiple metal ions and an oil phase containing a metal extractant as described in any one of claims 1 to 9.

11. A compound represented by the following formula (II), [Chemical Formula 3] In equation (II), R 1 This indicates a hydrogen atom, a metal atom, or a monovalent substituent. L represents a divalent linker containing at least one of the following: oxygen, sulfur, and phosphorus atoms, but not a nitrogen atom. R 2 It represents a hydrocarbon group with 8 or more carbon atoms. However, when L is a carbonyl group, it represents a hydrocarbon group with 8 or more hydrogen atoms. The benzene ring in formula (II) can form a fused ring.

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